Morteza Djamali

Indian summer monsoon variations could have affected the early Holocene woodland expansion in the Near East

Postglacial expansion of deciduous oak woodlands of the Zagros—Anti-Taurus Mountains, a major biome of the Near East, was delayed until the middle Holocene at ~6300 cal. yr BP. The current hypotheses explain this delay as a consequence of a regional aridity during the early Holocene, slow migration rates of forest trees, and/or a long history of land use and agro-pastoralism in this region. In the present paper, support is given to a hypothesis that suggests different precipitation seasonalities during the early Holocene compared with the late Holocene. The oak species of the Zagros—Anti-Taurus Mts, particularly Quercus brantii Lindl., are strongly dependent on spring precipitation for regeneration and are sensitive to a long dry season. Detailed analysis of modern atmospheric circulation patterns in SW Asia during the late spring suggests that the Indian Summer Monsoon (ISM) intensification can modify the amount of late spring and/or early summer rainfall in western/northwestern Iran and eastern Anatolia, which could in turn have controlled the development of the Zagros—Anti-Taurus deciduous oak woodlands. During the early Holocene, the northwestward shift of the Inter-Tropical Convergence Zone (ITCZ) could have displaced the subtropical anticyclonic belt or associated high pressure ridges to the northwest. The latter could, in turn, have prevented the southeastward penetration of low pressure systems originating from the North Atlantic and Black Sea regions. Such atmospheric configuration could have reduced or eliminated the spring precipitation creating a typical Mediterranean continental climate characterized by winter-dominated precipitation. This scenario highlights the complexity of biome response to climate system interactions in transitional climatic and biogeographical regions.

Olive cultivation in the heart of the Persian Achaemenid Empire: new insights into agricultural practices and environmental changes reflected in a late Holocene pollen record from Lake Parishan, SW Iran

Ancient Persia witnessed one of its most prosperous cultural and socio-economic periods between 550 bc and ad 651, with the successive domination of the Achaemenid, Seleucid, Parthian and Sassanian Empires. During this period agricultural activities increased on the Iranian plateau, as demonstrated by a remarkable arboricultural expansion. However, available data are not very informative about the spatial organization of agricultural practices. The possible links between climate conditions and agricultural activities during this millennium of continuous imperial domination are also unclear, due to the lack of parallel human-independent palaeoclimatic proxies. This study presents a new late Holocene pollen-based vegetation record from Lake Parishan, SW Iran. This record provides invaluable information regarding anthropogenic activities before, during and after the empires and sheds light on (i) spatial patterning in agricultural activities and (ii) possible climate impacts on agro-sylvo-pastoral practices during this period. Results of this study indicate that arboriculture was the most prominent form of agricultural activity in SW Iran especially during the Achaemenid, Seleucid and Parthian periods. Contrary to the information provided by some Greco-Roman written sources, the record from Lake Parishan shows that olive cultivation was practiced during Achaemenid and Seleucid times, when olive cultivation was significant, at least in this basin located close to the capital area of the Achaemenid Empire. In addition, pollen from aquatic vegetation suggests that the period of the latter centuries of the first millennium bc was characterized by a higher lake level, which might have favoured cultural and socio-economic prosperity.

Fossil beetles as possible evidence for transhumance during the middle and late Holocene in the high mountains of Talysch (Talesh) in NW Iran

Abstract A short sediment core (300 cm) was retrieved from a peaty deposit in the northeastern corner of Lake Neor in NW Iran yielding a 6500-year-old sequence relatively rich in pollen and beetle remains. Beetle assemblages contained a significant amount of coprophagous and coprophilous species all along the core. Pollen spectra suggest an open steppe landscape typical of the modern Irano-Turanian highlands with pollen indicators of agro-pastoral activities and also the proximity of the mesic temperate Hyrcanian forest to the east. Together, insect and pollen evidence, in agreement with the archaeological evidence for NW Iran, suggest that pastoralism was practised in the high elevation surroundings of Neor in Talysch Mountains at least since ca. 6500 years ago. This preliminary study highlights the strong potential of palaeoentomological investigations in furthering our understanding of the history of pastoralism in the Middle East.

Landscape evolution and agro-sylvo-pastoral activities on the Gorgan Plain (NE Iran) in the last 6000 years

The Gorgan Plain (NE Iran) is characterized by fertile soils formed on a loess plateau and is at present primarily exploited for intensive agriculture. However, the timing and intensity of the human impact on the landscape in the past are still unclear. A sediment core, taken from the centre of the eastern Gorgan Plain in the Kongor Lake covering the major part of the Holocene from 6.1 to 0.8 ka (all ages are calibrated before present), has been studied for pollen, non-pollen palynomorphs, botanical macroremains, insects, charcoal, geochemistry, biomarkers and magnetism in order to provide new insights into the evolution of the landscape and to estimate the intensity of human activities. The data obtained suggest a dry period between 5.9 and 3.9 ka and an increase in regional humidity afterwards with a maximum between 2.7 and 0.7 ka, during the period of the Persian empires (Achaemenid through Sasanian) and the Islamic era. The eastern part of the Gorgan Plain was characterized by open steppe landscapes during the last 6 ka, which most likely were used for pasture and at least since 2.7 ka for agriculture including arboriculture. The strongest anthropogenic impact on the environment around the Kongor site is documented during the Parthian and Sasanian Empires (200 BC–651 AD) and the Islamic era up to the eve of the Mongol invasion.

Past and future global transformation of terrestrial ecosystems under climate change

Future predictions from paleoecology Terrestrial ecosystems will be transformed by current anthropogenic change, but the extent of this change remains a challenge to predict. Nolan et al. looked at documented vegetational and climatic changes at almost 600 sites worldwide since the last glacial maximum 21,000 years ago. From this, they determined vegetation responses to temperature changes of 4° to 7°C. They went on to estimate the extent of ecosystem changes under current similar (albeit more rapid) scenarios of warming. Without substantial mitigation efforts, terrestrial ecosystems are at risk of major transformation in composition and structure. Science, this issue p. 920 Global vegetation change since the Last Glacial Maximum is used as an indicator of transformation under warming scenarios. Impacts of global climate change on terrestrial ecosystems are imperfectly constrained by ecosystem models and direct observations. Pervasive ecosystem transformations occurred in response to warming and associated climatic changes during the last glacial-to-interglacial transition, which was comparable in magnitude to warming projected for the next century under high-emission scenarios. We reviewed 594 published paleoecological records to examine compositional and structural changes in terrestrial vegetation since the last glacial period and to project the magnitudes of ecosystem transformations under alternative future emission scenarios. Our results indicate that terrestrial ecosystems are highly sensitive to temperature change and suggest that, without major reductions in greenhouse gas emissions to the atmosphere, terrestrial ecosystems worldwide are at risk of major transformation, with accompanying disruption of ecosystem services and impacts on biodiversity.

PALEOLIMNOLOGY OF LAKE HAMOUN (E IRAN): IMPLICATION FOR PAST CLIMATE CHANGES AND POSSIBLE IMPACTS ON HUMAN SETTLEMENTS

Abstract: Environmental changes since the late deglaciation are reconstructed from the sediment of Lake Hamoun. Lake Hamoun is located at the border of Iran and Afghanistan where inflowing rivers originate from the drainage basins of SW Hindu Kush Mountains and westernmost Himalaya. The lake has experienced a complex hydrological history during the late Quaternary due to climatic changes. Geochemical, sedimentological, and paleontological proxies as well as geomorphological data were used to investigate environmental changes of the lake. The results demonstrate that since the late glacial, the basin has directly and/or indirectly received its moisture from various climatic systems. During the early Holocene, both the Indian summer monsoon (ISM) and the mid-latitude westerlies (MLW) intensified and consequently the basin received higher precipitation. This interpretation is supported by higher content of total organic matter (mean: 8.2%), finer-grained sediments with low δ18O values (mean: -3.5‰), as well as rich fossil content. Lower organic matter content (< 5%), higher magnetic susceptibility values (5.8–10×10−4 SI unit), and coarser-grained sediments with no shell fragments support the dominance of an arid environment during the early-mid Holocene. The results of stable isotopes suggest weakening of ISM and intensification of MLW during the mid-late Holocene in the study area, when Bronze Age civilizations emerged in the Sistan Basin. In the late Holocene, lake levels experienced more severe fluctuations due to variations in the MLW. Shifts in settlement areas seen in the archaeological record may thus have been a response to climatic changes.

Wild grapevine (Vitis vinifera subsp. sylvestris) in the Hyrcanian relict forests of northern Iran: an overview of current taxonomy, ecology and palaeorecords

Abstract Due to severe anthropogenic impacts on lowland and submontane zones of the Hyrcanian forests of northern Iran, wild grapevine (Vitis vinifera subsp. sylvestris), a sporadically distributed woody liana, is currently considered an endangered species. Using data from the literature and 34 studied populations, herbarium assessments and nine palynological sites, we provide an overview of its taxonomy, distribution and ecology in the first part of the investigation. The separation of the two subspecies, namely V. sylvestris subsp. anebophylla and V. sylvestris subsp. trichophylla (sensu Flora Iranica), based on their leaf indumentums, could not be confirmed by our examination of herbarium materials and field observations. Indumentum of the leaves is a result of leaf polymorphism in different Vitis specimens and can be strongly influenced by environmental conditions. Vitis vinifera subsp. sylvestris grows in a wide range of habitats including wetlands, seasonal stream sides in closed forests, alluvial beds of large rivers, sand dune shrublands and forested wetlands (alder forests). Parrotia persica and Carpinus betulus were the most frequent host species in the studied populations. In the Hyrcanian region, no pollen record of Vitis older than the Mid-or Late-Holocene has yet been established. Despite the intrinsic problem in pollen identification by normal (i.e., light) microscopy of wild from cultivated grapevines, the significant values and persistent occurrence of Vitis pollen since the Mid-Holocene (before the Bronze Age) in the Hyrcanian pollen records may imply the onset of viticulture in low- to mid-elevation sites in the region. This represents an argument to consider the Hyrcanian region as a possible domestication center for V. vinifera. However, the question of wild versus cultivated origin of grapevines in the Hyrcanian pollen records and the possible date of its domestication and/or cultivation will remain open until further palynological studies are undertaken.

A note on the biogeographical origin of the brine shrimp Artemia urmiana Günther, 1899 from Urmia Lake, Iran

The brine shrimp Artemia urmiana, an abundant inhabitant of the hypersaline Urmia Lake in northwestern Iran, has recently been described from Lake Koyashskoe, also a shallow hypersaline lake that is located on the Black Sea coast of the Crimean Peninsula (Ukraine). This discovery has questioned the endemicity of A. urmiana in Urmia Lake and has also brought into question the biogeographical origin of this species. In the present study, we combined recent genetic divergence data (mtDNA-COI) with palaeoecological evidence to address the biogeographical origin of A. urmiana. Calibration of the molecular clock of the COI region was set by assigning the age of the micro-crustacean Daphnia pulex minimally at 145 Mya. The divergence age of A. urmiana in Urmia Lake dates back to 383,000 years, whereas Ukrainian Artemia reflects a very young populations that diverged about 196,000 years ago. Palaeoecological evidence suggests that the age of the major habitat of A. urmiana i.e. Urmia Lake goes back to the Tertiary Period while the Ukranian habitats of the species are very young, by virtue of geological features of the Holocene age. We conclude that the biogeographical origin of A. urmiana is outside of Europe and the current state of knowledge strongly suggests that Urmia Lake has been the major source of its expansion into its modern habitats in Europe.